Adsorptive Removal of Selected Halogenated Pharmaceuticals from Water Using Iron Modified Kenyan Natural Zeolite: An Experimental Study

Abstract

A worldwide basic human right is the availability of affordable, trustworthy, and safe water. Pollutants of emerging concern like halogenated pharmaceuticals have been documented in all environmental matrices. Their adverse effects on humans and biota necessitate the need for their removal from water. The remediation of pharmaceuticals from water is a growing concern since conventional wastewater treatment plants are not equipped effectively for the task. Owing to its simplicity of use, affordability, and environmental friendliness, adsorption using natural and modified adsorbents appeals as a method of remediation. This study investigated the adsorptive potential of iron-modified Kenyan zeolite by varying contact time, initial pollutant concentration, temperature, and pH, while employing spectrophotometric monitoring. Adsorbent characterization using EDS, XRD, SEM, FTIR, and point of zero charge analyses provided insights into the structural and chemical changes brought by iron modification. The sorption capacity of unmodified zeolite was 7.71, 4.35, and 5.19 mg/g for Chloramphenicol, Ciprofloxacin, and Diclofenac potassium, respectively, while iron- modified zeolite exhibited significantly higher capacities of 22.49, 18.43, and 15.70 mg/g, respectively. Kinetic studies revealed that Chloramphenicol adsorption followed a pseudo-first order model, while Ciprofloxacin and Diclofenac potassium adhered to a pseudo-second order model. Isothermal analyses indicated that Chloramphenicol and Diclofenac potassium adsorption better fitted to the Freundlich model, whereas Ciprofloxacin was well described by the Temkin model. Thermodynamic analysis confirmed that adsorption onto iron-modified zeolite was spontaneous and feasible for all pollutants, with adsorption of Chloramphenicol and Diclofenac potassium being exothermic and Ciprofloxacin’s showed endothermic characteristics. These findings highlight the superior performance of iron-modified Kenyan zeolite as an affordable and efficient adsorbent for pharmaceutical pollutant removal, offering a promising solution for water treatment. Keywords: Iron-modified zeolite, Diclofenac potassium, Chloramphenicol, Ciprofloxacin